1. Field of the Invention
The present invention relates to a video transmission system of a ring network. Specifically, the present invention relates to a video transmission system for implementing a new video transmission method.
2. Description of the Related Art
Conventionally, in a video transmission system for transmitting a video signal such as HDTV (High-Definition Television) signal and SDTV (Standard-Definition Television) signal, respective video transmission apparatuses are connected in a point-to-point (P to P) configuration, thereby transmitting video. The reason for this is that high-quality video is required for broadcasting, and in terms of its purpose, it is necessary to prevent interruption and distortion of the video utilized for broadcasting. Therefore, video transmission is carried out by means of special connection line between apparatuses in order to prevent reception of other spurious signals, thereby transmitting high-quality video.
Between video transmission apparatuses connected in a point-to-point configuration, transmission paths are required based on the number of SDTV signals and HDTV signals. For example, in Unexamined Japanese Patent Application Publication No. 2001-16554, a video transmission method, which can transmit a plurality of video signals by a simple transmission path, and is flexibly adjustable to vary the number of signals to be transmitted. In the Unexamined Japanese Patent Application Publication No. 2001-16554, a control signal, including information on the type of signal to be multiplexed, and on number of signals to be multiplexed, is generated in the transmitter side, and the control signal and video signal are multiplexed and are transmitted to the transmission path, so that receiver side can control the type and number of video signals, to be demultiplexed, based on the control signal.
Further, a method, in which by means of optical wavelength multiplexing, a plurality of signals are multiplexed, and are transmitted to a simple transmission path, has been used.
In the conventional technology, a video signal is transmitted by means of a simple transmission path connected in a point-to-point configuration. In the system, for example as shown in FIG. 10, in cases where a video transmission apparatus a utilizes video signal (video source), transmitted via another transmission path x, which is not connected to the apparatus itself, it is necessary that the video signal is once acquired by a video transmission apparatus b, which is connected to another transmission path x, and is re-transmitted to a transmission path y, which is connected to the video transmission apparatus a. Therefore, when acquiring the video source transmitted via the transmission path x, complex processes are required, or the acquisition of video source is impossible depending on configuration of the transmission path.